1. Field of the Invention
With regard to the classification of art, this invention is believed to be found in the general class entitled MACHINE ELEMENTS OR MECHANISMS and more particularly to those subclasses pertaining to HYDRAULICALLY OPERATED ROTARY VIBRATORS.
2. Description of Related Art
Hydraulically operated rotary vibrators have been previously disclosed in the art. Generally the systems consist of at least one vibrator assembly that is coupled to an independent hydraulic motor. It has been found that this type of arrangement places a great deal of stress on the drive coupling. That stress generally results in failure of the connection. This type of arrangement is also energy inefficient, by needing to overcome the power requirements of the individual components. Another known arrangement directly attaches the hydraulic motor to a shaft of the rotary vibrator. This direct connection has been found to also have disadvantages. One of the known disadvantages is that the bearings of the hydraulic motor are prone to premature failure. These bearings generally are of the needle bearing type or the sleeve type because of size restrictions of the gear centers within the motor housing. The typical hydraulic motor is primarily rated on its torque rating. The rating and subsequent selection by torque alone may result in hydraulic motor that is undersized for the total of the vibratory forces that are developed. The selection of smallest hydraulic motor is attractive to a company because it reduces the cost of the vibrator assembly. Another disadvantage of this type of construction is the cost of the many components.
U.S. Pat. No. 2,988,338, issued to Fors et al on Jun. 13, 1961 discloses a rotary vibrator with an integral hydraulic motor. This patent was directed to reducing the cost associated with manufacturing hydraulically driven rotary vibrators. However this patent discloses a gear arrangement which may be described as a planetary arrangement. This planetary arrangement also has dimensional restrictions which also require the use of needle bearings. These small diameter needle bearings are also believed to be subject to a high failure rate.
The construction disclosed in the instant invention overcomes the problem of bearing failure by using large bearings. The construction of the vibrator disclosed in the instant invention also solves the problem of high cost that is associated with the production of the prior art hydraulically powered rotary vibrators. An unexpected benefit was realized with the construction of the present invention. This benefit allows the eccentrics to be adjusted relative to each other to provide a range of vibration forces. This range may be varied in increments from a minimum to a maximum value for a given size unit.